Toyota Repair: 92 Camry Low Idle, air control valve, stop signs

Question
I have a 92 Camry which has been exceptionally reliable.  However when the engine is hot and we attempt to restart, the idle speed is very low (500 - 700 rpms).  Idle speed stays low for a few minutes after starting (i.e. at stop signs, stoplights)..then improves slightly. This has been getting progressively worse.  Cold start is not great, but low idle is much worse when restarted on a hot engine.  The idle is so low the lights come on as if the engine is off, but it is still on, we have to press the accelerator.
Any advice greatly appreciated

Answer
This is a very common problem and I have answered it many times, the problem is the idle speed control valve(ISC valve) sometimes called the idle air control valve, all it does is control the idle speed of the engine, if it becomes gummed up with deposits it will stick and cause idle problems, it is located on the throttle body which has to be removed from the intake chamber to gain access to the ISC valve, then it can be removed and either cleaned or replaced, if the car has a lot of miles I recommend replacing it.